CONFOCAL MICROSCOPY SHARED RESOURCE David McClay, Ph.D., Richard Fehon, Ph.D., Co-Directors The Confocal Microscopy Shared Resource provides a state-of-the-art Facility for obtaining images of cells in which single molecules are tagged with fluorescent markers. By confocal microscopy and computation methods, 3-D images resolve the spatial location of any tagged molecule in cells, tissues or organisms. The Facility provides training for use of the microscope and the microscope plus computational components are maintained and frequently upgraded. The Confocal Microscopy Shared Resource supports more than 47 laboratories in the Cancer Center. In recent years the Facility has been booked for more than 98% of available time and used by more than 100 different investigators per year. The output of papers that include confocal instrumentation is high. Over the past five years more than 80 papers plus 10 journal covers come from facility usage. This proposal provides a list of upgrades and eventual replacement of the Zeiss 410 instrument that constitutes the Facility. There will be a continuation of policies that kept the instrument on line for all but 4 days in 2003. This will maximize availability of the instrument. Fee charges will be kept at the minimum necessary to keep the instrument in operation at a high efficiency. Policies for maintaining the instrument as a high quality and effective tool for obtaining confocal images will be continued. A new instrument will be purchased in about two years in order to provide the community with a state-of-the-art facility.